error_on_undefined_vars doesn't work for role parameters

[jack.ma...@gmail.com]

I was going to submit this as a bug but I decided to send email first in case I'm doing something wrong.

The session below should show all required information, but let me know whether something else is needed.

ansible$ cat playbooks/test_role_with_undefined_list.yml                                                                                                      
---
- hosts: 127.0.0.1
  connection: local

  roles:
    - { role: ansible_tests/debug_loop_on_list, list_of_items: '{{ possibly_undefined_list }}' }
ansible$ cat roles/ansible_tests/debug_loop_on_list/tasks/main.yml
- name: do something in a loop
  debug: msg="loop var is '{{ item }}'"
  with_items: list_of_items
ansible$ ansible-playbook -e '{ "possibly_undefined_list":[ "apple", "orange" ] }' playbooks/test_role_with_undefined_list.yml                                

PLAY [127.0.0.1] **************************************************************

GATHERING FACTS ***************************************************************
ok: [127.0.0.1]

TASK: [ansible_tests/debug_loop_on_list | do something in a loop] *************
ok: [127.0.0.1] => (item=apple) => {
    "item": "apple",
    "msg": "loop var is 'apple'"
}
ok: [127.0.0.1] => (item=orange) => {
    "item": "orange",
    "msg": "loop var is 'orange'"
}

PLAY RECAP ********************************************************************
127.0.0.1                  : ok=2    changed=0    unreachable=0    failed=0  

ansible$ ansible-playbook playbooks/test_role_with_undefined_list.yml                              

PLAY [127.0.0.1] **************************************************************

GATHERING FACTS ***************************************************************
ok: [127.0.0.1]

TASK: [ansible_tests/debug_loop_on_list | do something in a loop] *************
ok: [127.0.0.1] => (item=list_of_items) => {
    "item": "list_of_items",
    "msg": "loop var is 'list_of_items'"
}

PLAY RECAP ********************************************************************
127.0.0.1                  : ok=2    changed=0    unreachable=0    failed=0  

ansible$ cat - >/dev/null
EXPECTED BEHAVIOR ABOVE WAS:

Error: list_of_items is undefined.

ansible$ ansible --version
ansible 1.8.4
  configured module search path = None
ansible$ grep error ansible.cfg
# by default (as of 1.3), Ansible will raise errors when attempting to dereference
#error_on_undefined_vars = False
ansible$ find roles/ansible_tests/debug_loop_on_list/ -type f                                                                                                
roles/ansible_tests/debug_loop_on_list/tasks/main.yml
ansible$

[jack.ma...@gmail.com]

Actually.. possibly_undefined_list should have thrown an undefined error before you ever try to access list_of_items on the second run.